This invention relates to snap acting electric switches of the type wherein snap acting movement of a fulcrumed switch blade is caused by applying lateral pressure to spring means which normally holds the switch blade in one of its two positions.
In the past, switches of this general type have been actuated by actuator plungers which are mounted for sliding movement transversely of the actuator springs. Such actuator plungers have an external portion which extends outside the switch housing through an opening therein and have an inside portion that is positioned to engage the actuator spring and move it laterally. However, this type of switch has the disadvantage that the actuator plunger acts as a piston and pushes air out of the interior of the switch housing when the plunger is pushed inwardly to actuate the switch, and then draws air back into the switch housing when the actuator plunger returns to its rest position. This breathing action of the switch draws dust particles into the switch housing and thus tends to reduce the reliability and lifetime of the switch.
Also, the requirement that the actuator plunger must be movable transversely of the actuator spring puts a limitation on the position of the actuator plunger and sometimes requires the use of a separate actuator arm positioned to bear against the actuator plunger as disclosed, for example, in U.S. Pat. No. 3,073,923. The use of a separate actuator arm increases both the size and the cost of the switch.